The dura mater, occurring between the cranial bones and brain and covering the spinal cord, protects the brain and spinal cord and inhibits leakage of cerebrospinal fluid. In the field of neurosurgery, a defect or contracture of the dura mater used to be filled with lyophilized products of human dura mater.
However, the lyophilized products of human dura mater have had drawbacks such as low homogeneity and short supply. Further, a possible transmission of infection of Creutzfelt-Jacob disease through the use of the human dura mater was reported (Noshinkeigeka; 21(2), 167-170, 1993) and, eventually, the Japanese Ministry of Health and Welfare banned the use of the lyophilized product of human dura mater on Apr. 7, 1997.
To solve the above drawbacks, artificial dura mater made of silicone, for example, was developed. However, the silicone dura mater has fallen into disuse as it was reported that the silicone dura mater predisposed to meningorrhagia by remaining in vivo permanently because it was non-biodegradable, whereby being a chronic stimulant for the surrounding tissue to cause hypertrophy of the granulation tissue.
In contrast, artificial dura maters made of biodegradable and bioabsorbable materials such as collagen (Journal of Biomedical Materials Research; Vol. 25, 267-276, 1991) and gelatin (No to Shinkei; 21 1089-1098, 1969) were produced, but they were not in practical use because of strength-related problems, i.e., because of the insufficiency in the suture strength to be sutured integrally with the internal dura mater.
The applicant provided, in Japanese Unexamined Patent Publication No. 8-80344, an artificial dura mater comprising a sheet made of a biodegradable and bioabsorbable polymer, for example, a copolymer of lactic acid and caprolactone and, further, an artificial dura mater comprising introducing a biodegradable and bioabsorbable polymer made of a material different from that of the sheet as a reinforcement between the sheets and integrally molding the sheets and the reinforcement.
The present invention relates to improvements in the artificial dura mater disclosed in the above publication. An object of the present invention is to provide an artificial dura mater improved in qualities such as non-leakage and suture strength, and a process for producing the same.